This week, we review a little and also study the final topic: How torque is the rate of change of angular momentum, and how they are both vectors, so when torque is perpendicular to angular momentum, torque doesn’t increase or decrease angular momentum. Instead, torque causes the angular momentum to change direction. This is precession.
Monday we review a little to get back in shape from the week gone by. Be ready to finish your projects.
Before Class
- See video on Inclined Plane using Only Energy (no kinematics at all!) (3.5 minutes)
- See this short video on Angular Momentum and Figure Skating
- See Veritassium video on how angular momentum provides increased stability against rotation.
- Please watch this very short video of something you should never never do. Please ask yourself what happened here and why the one boy was hurt and not the other.
- Please see: Explanation of Veritassium Bullet Problem
- Please see solutions to MT#2, posted on main class website.
- Work on your project #2!
- Finish PS#9 on main class website.
During Class
- Why must we spin frisbees or footballs to make them fly stable?
- Precession – what is it?
Tuesday: We look at angular momentum as stability.
Before Class
- I’ve posted your feedback from yesterday’s class on the main class website, and made some comments. In particular, if you’re interested in more of this kind of learning, please consider taking one of my other classes: Energy, Society, and the Environment (PSc 320, winter quarter), Appropriate Technology Classes (PSc 391 in Fall, PSc 392 Spring – 391 is not a prerequisite for 392)
- Please take this short Survey #9
- Here is a precession video I made recently to explain precession. It’s likely my most well-received video to date.
- read 7.5 in your text about precession.
- See video on how gyroscopes can stabilize boats. You might consider how this video compares/contrasts with the Veritassium video from yesterday. I spent more time on this video than any other video I’ve made. Please let me know if it was worth it.
- Please look over these activities on Gyroscope Worksheet. Can you try some of them?
- Group project is due this weekend, Midnight Saturday night. Please post the website for your youtube video – make sure it’s public so I can see it.
- I posted PS#10 on the main class website. Please have a look as soon as possible.
In Class
- What is precession?
- We will execute these activities on Gyroscope Worksheet.
After Class
Post Video Project by midnight Saturday night.
Wednesday
- PS#10 posted on main class website. Please check out the problems!
- Solutions for PS#8 and PS#9 posted on main class website.
- I’ve posted your feedback from yesterday’s class on the main class website, and made some comments. In particular, if you’re interested in more of this kind of learning, please consider taking one of my other classes: Energy, Society, and the Environment (PSc 320, winter quarter), Appropriate Technology Classes (PSc 391 in Fall, PSc 392 Spring – 391 is not a prerequisite for 392)
- Hey, so you saw the video yesterday about gyroscopic stabilization. THEN we did our activity. NOW, please watch the video explaining Gyroscopic stabilization. This is the video I spent so much time on. Be ready to let me know tomorrow if this helps explaining the concept.
- Read up a little on counter steering.
- Please see Precession by Veritassium , a super professionally made video. You’ll let me know if it’s more helpful than my video.
- See work on an inclined plane video.
- Consider joining Engineers for a Sustainable World (ESW).For more information, see this ESW flyer.
During Class
- What is counter steering on a motorcycle?
Thursday
Before Class
- Hey, so having covered precession and gyroscopic stabilization, we’ve completed the conceptual content of the class! OMG, we’re done? The rest of the class is about review and increased examples. So, dig in! Learn what you might be weak on… prepare for the final exam.
- Hey, only about half of you watched the video explaining Gyroscopic stabilization from yesterday’s assignment. Additionally, many people expressed confusion with the concept. In my eyes, this means that we’re finally struggling to understand the concept on a deeper level. If you haven’t watched it, please do. If you are confused, please consider watching it again and coming into class with questions tomorrow.
- Please do PS#10, posted on main class website – not due until next Monday.
- Read 7.6 on two irrelevant equations and trigonometry that you are allowed to use now.
- See Trigonometry Video , now you’re allowed to use trigonometry, but remember you can also always draw a picture if you’re not sure.
- See 1D, 2D Kinematics Video and then you’re allowed to use those two unnecessary (in my opinion) equations, although hopefully, you’ve realized by now that you can get along without them just fine.
- Optional: Here is an old precession video I made a few years ago. It’s long and slow with lousy graphics, but it has well over 3000 views, so some people found it helpful: Pete’s OLD Precession Video .
During Class
- Big Exam! #7
- finding coefficient of friction
After Class
Post your video link before midnight this Saturday!